Design of Leaky-Wave Antenna With Wide-Angle Backfire-to-Forward Beam Scanning Based on Generalized Pattern Synthesis

Frequency-scanning antenna has been extensively explored in radar and vehicle communication systems, but it is a challenge to provide methodological guidance to achieve a wide scanning angle. Here, a generalized pattern synthesis method is proposed and a leaky-wave antenna with wide scanning range is designed to verify the technique. First, a generalized antenna element (GAE) is presented, whose main beam can steer continuously with frequency. Meanwhile, the phase constant of the leaky wave determines the beam direction of the array factor. Then, a leaky-wave antenna can steer with a large beam scanning angle and stable gain as patterns of the array factor and the GAE are manipulated simultaneously. To verify, a prototype SIW LWA with double-layer transverse slots is fabricated and measured. Experimental results show this antenna achieves continuous dual-beam scanning from backfire ( $-{\mathrm {90}}^{\circ }$ ) to forward $(\pm 20^{\circ })$ from 12.4 GHz to 19.9 GHz with a total coverage range of 220° and the realized gain varying from 8.3 dBi to 12.8 dBi.

I. Introduction

Leaky-wave antenna (LWA) is a type of antenna that supports wave traveling on a guiding wave structure [1]. Due to the capability of frequency-dependent beam scanning and reduction in the number of T/R components [2], LWA is widely used in modern wireless communication systems such as tracking radars [3], [4], automotive radar sensors [5] and it shows great potential in prospective 5G-Internet of Things [6], vehicle communication, building wireless links between multiple objects and other application [7]. In the early time, the first known leaky-wave antenna was proposed by W. W. Hansen in 1940 [8]. Then the fast-developed LWAs can be divided into two categories according to their structures and radiation mechanism: uniform [9] and periodic LWA [10]. Another category of LWA based on a quasi-uniform structure is also developed by choosing the period smaller enough compared to the wavelength, such as composite right/left-handed (CRLH) LWAs [11], [12].